A Single Brain Structure May Give Winners That Extra Physical Edge

Recent studies indicate that the brain's insular cortex may help a sprinter drive his body forward just a little more efficiently than his competitors.
(Matthias Kulka / Corbis)

By
Sandra Upson

smithsonian.com
July 25, 2012

All elite athletes train hard, possess great skills and stay mentally sharp during competition. But what separates a gold medalist from an equally dedicated athlete who comes in 10th place? A small structure deep in the brain may give winners an extra edge.

Recent studies indicate that the brain's insular cortex may help a sprinter drive his body forward just a little more efficiently than his competitors. This region may prepare a boxer to better fend off a punch his opponent is beginning to throw as well as assist a diver as she calculates her spinning body's position so she hits the water with barely a splash. The insula, as it is commonly called, may help a marksman retain a sharp focus on the bull's-eye as his finger pulls back on the trigger and help a basketball player at the free-throw line block out the distracting screams and arm-waving of fans seated behind the backboard.

The insula does all this by anticipating an athlete's future feelings, according to a new theory. Researchers at the OptiBrain Center, a consortium based at the University of California, San Diego, and the Naval Health Research Center, suggest that an athlete possesses a hyper-attuned insula that can generate strikingly accurate predictions of how the body will feel in the next moment. That model of the body's future condition instructs other brain areas to initiate actions that are more tailored to coming demands than those of also-rans and couch potatoes.

This heightened awareness could allow Olympians to activate their muscles more resourcefully to swim faster, run farther and leap higher than mere mortals. In experiments published in 2012, brain scans of elite athletes appeared to differ most dramatically from ordinary subjects in the functioning of their insulas. Emerging evidence now also suggests that this brain area can be trained using a meditation technique called mindfulness—good news for Olympians and weekend warriors alike.

Peak performance

Stripped of the cheering fans, the play-by-play commentary and all the trappings of wealth and fame, professional sports reduce to a simple concept: The athletes who enthrall us are experts at meeting specific physical goals. They execute corporeal feats smoothly, without wasting a single drop of sweat.

Such performance is a full-brain phenomenon. The motor cortex and memory systems, for example, encode years of practice. Nerve fibers become ensconced in extra layers of a protective sheath that speeds up communication between neurons, producing lightning-fast reflexes. Understanding the brain at its athletic best is the goal of psychiatrist Martin Paulus and his colleagues at the OptiBrain Center. They propose that the insula may serve as the critical hub that merges high-level cognition with a measure of the body's state, to insure proper functioning of the muscles and bones that throw javelins and land twirling dismounts from the high bar. "The key idea we're after is how somebody responds when they get a cue that predicts something bad will happen," Paulus says. "The folks that are performing more optimally are the ones who are able to use that anticipatory cue to adjust themselves and return to equilibrium."

Slightly larger than a kumquat, the insula is part of the cerebral cortex, the thick folds of gray tissue that form the brain's outer layer. The densely rippled structure sits on the inside of the cortical mantle, resembling a tiny Japanese fan tucked neatly into the brain's interior. It is commonly thought of as the seat of interoception, or the sense of your body's internal state.

The insula generates this sense by maintaining a map of all your far-flung organs and tissues. Certain neurons in the insula respond to rumblings in the intestines, for example, whereas others fire to reflect a toothache. To manage the influx of messages bombarding it from throughout the body, the insula collaborates closely with the anterior cingulate cortex, an area crucial for decision-making, to evaluate and prioritize those stimuli. This raw representation of bodily signals has been hypothesized for more than a century to be the origin of emotions.

At first glance, pegging the insula as critical to anything can seem almost meaningless. It has been implicated in functions as diverse as decision-making, anticipation, timekeeping, singing, addiction, speech, even consciousness. The insula and the anterior cingulate cortex are the most commonly activated regions in brain-imaging experiments, according to a 2011 study, making it all the more difficult to discern their core functions.

Nevertheless, the case for the insula as the hub of athleticism has been building slowly for more than a decade. In the late 1990s neuroanatomist A. D. Craig at Barrow Neurological Institute was mapping the pathways that deliver pain and temperature sensations to the brain through the spinal cord. Upon discovering that these conduits led to the insula, he posited that one of the brain's core functions is to help the body maintain homeostasis, or equilibrium. For example, the body's internal temperature usually stays within a narrow range, and perturbations, registered by the insula, motivate us to restore it to that comfortable zone—perhaps by drinking cool water, seeking a shady patch or ceasing movement. Indeed, when scientists damaged the insula in rats, their ability to regulate their bodies was impaired.

When we exercise, we agitate our internal state. "Everything we do requires a calculation of how much energy it costs us, and this is what the insula seems to be performing," Craig says. By predicting how certain exertions will affect the body, the brain can initiate actions to temper those perturbations before they happen.

A compelling study from 2004 showed clear anatomical differences that matched variation in interoceptive ability. Hugo Critchley, now at the University of Sussex in England, asked participants to estimate the rate at which their hearts were beating without taking their own pulses. The people who guessed their heart rates most accurately had greater activity in the insula and more gray matter in this region. That last point is crucial, because it suggests that the physical size of the insula is directly related to differences in ability. This neural imprinting is similar to what is seen in professional violinists, whose motor cortex devotes greater real estate to the representations of fingers than is seen in an amateur's brain.

The OptiBrain researchers hypothesized that athletes need to be intensely aware of sensations such as heartbeat—and capable of recognizing the important ones and dismissing the red herrings. "The vast majority of NBA players are amazing athletes. But some of them stand out. It's not that Kobe Bryant or Derrick Rose has more energy, it's how they choose to expend that energy in critical moments that will decide their success," clinical psychologist Alan Simmons at the Veterans Affairs San Diego Healthcare System says.

Thinking ahead

To test the idea that extremely fit individuals have superior interoception—and to investigate what this superiority looks like in action—Paulus and Simmons recently recruited a group of elite athletes to lie in a scanner and perform cognitive tests while an apparatus restricted their breathing. The feeling of shortness of breath is an unpleasant sensation that is known to rev up the insula.

Paulus and Simmons tested 10 of the world's most accomplished adventure racers—men and women who perform wilderness challenges that can include climbing, swimming, running and paddling. They asked the racers and 11 healthy control subjects to lie in a scanner and breathe through a tube while wearing a nose clip. While in the magnetic resonance imaging (MRI) machine, the subjects were instructed to view arrows pointing either left or right on a screen and press a button to note the direction. Sporadically, the researchers adjusted the airflow so that breathing became significantly more difficult. A change in the screen's color alerted the participants that breathing was about to become labored. The color change did not always accurately predict breathing restriction, however.

In all phases of the experiment, the insula was active, but to varying degrees. The healthy volunteers performed equally well on the arrow tests throughout the study—with no interference, when the screen’s color changed and when struggling to inhale. But the adventure racers got more answers correct when either anticipating or undergoing the breathing load. Perturbing these individuals' interoceptive experience actually improved their performances. The racers also showed more brain activation when anticipating the breathing restriction but not while experiencing the restriction itself. It was as if the racers' brains made better use of cues to prepare themselves, thus gaining a cognitive edge. When the challenging moment arrived—when their breathing became labored—their insulas were comparatively placid.

Another study from Paulus's group, also published in 2012, adds nuance to this finding. The group sought to investigate elite athletes' cognitive flexibility. Considered a landmark of intelligence, this skill involves switching easily between opposing demands. Mental agility can plummet in a trying situation, however. Experiments on Navy SEALs and Army Rangers revealed that exposure to combatlike conditions impaired their reaction times, vigilance, learning, memory and reasoning. For Olympic-level athletes, too, grace under fire is a major objective.

To observe cognitive flexibility in action, Simmons asked 10 Navy SEALs and 11 healthy male civilians to perform a simple task in a brain scanner. Navy SEALs are extremely athletic individuals who are trained to cope with great demands on their physical, mental and emotional faculties. The exercise involved observing either a green or red shape followed by an emotionally laden photograph on a screen. Participants were to press one button when they saw a circle and another when they viewed a square. A green shape signaled that a positive image (such as a child playing) would follow; a red shape indicated that a negative picture (for example, a combat scene) would appear next. The subjects were then judged on their speed and accuracy in identifying the shapes.

Compared with healthy participants, the elite warriors sent more blood coursing through their insulas and a few other regions when the shapes' colors differed in consecutive trials. In short, they were more aware of the impending switch from positive to negative or vice versa and engaged brain systems involved in modulating emotional and interoceptive responses. They were quicker to prepare for a looming shift in their internal states, buying their brains time to tamp down their reactions.

Taken together, the studies indicate that men and women who have extreme physical abilities show greater insula activation when anticipating a change to their internal feelings, whether emotional or physical.

"To me that's really huge if you have a region of the brain that's anticipating a response and preparing the body for it," physiologist Jon Williamson at the University of Texas Southwestern Medical Center says. "If an athlete is approaching a hill and can anticipate the delivery of blood to muscles, he or she may perform better on that hill."

The studies so far have been small, however—it's not easy to corral top-tier athletes into brain-imaging labs—so larger experiments are still needed to firm up the observations. Even so, the results echo earlier findings on the insula's involvement in imagining the future, whether anticipating physical pain from, say, a boxer's punch or contemplating the purchase of an overpriced item.

To Simmons, the evidence suggests that the insula does not live in the present, but the future. "We're responding to information incorporated from physiology, cognition, our surroundings," Simmons says. "By the time we've integrated all that, it's part of the past." The ability to forecast can also backfire, producing disorders such as anorexia nervosa, which combines lapses in bodily awareness with a concern for how food consumption now will alter body image in the future. "It's the anticipation that's getting in your way," Simmons says. Indeed, brain scans of individuals with eating disorders and post-traumatic stress disorder show that insula activity diverges from that seen in healthy subjects, suggesting impairments in this area.

Train your interoception

For aspiring athletes or individuals who suffer insular dysfunction, there are reasons to hope interoception is trainable. A meditation technique called mindfulness encourages people to tune into their present thoughts, emotions and bodily sensations. Derived from Buddhist teachings, this training seeks to heighten awareness of feelings but also to temper our reactions to them. The OptiBrain researchers have collected preliminary data, not yet published, suggesting that healthy subjects and military personnel who received mindfulness training improved in cognitive performance during a stressful situation—as measured with a breathing-restriction task—and reacted to challenges with less emotion, with the insular activation changes to match.

Small-scale studies on athletes, too, show benefit. This awareness of the feeling of the moment has been shown, for example, to improve the success of basketball players on the free-throw line. Sports psychologist Claudio Robazza at the University of Chieti in Italy has seen firsthand how mindfulness and similar techniques can single out successful athletes. He has worked for six years with Italy's Olympic shooting team, a mentally demanding sport that favors individuals who can still nail their targets when the pressure is highest. "Emotional states can reflect bodily changes, an increase in heart rate, muscular tension and breathing—all those things cause changes in the performance and the final outcome," Robazza says. "Certainly athletes need to be aware of their responses."

With tens of thousands of people gazing down from stadium seats, and millions more tuned in to television broadcasts, an Olympic athlete runs a high risk of choking. The stress of the moment can trigger many physical changes that interfere in the execution of even the most deeply ingrained maneuvers. A heightened awareness of the body's condition, facilitated by the insula, can alert a champion to tensed muscles or shallow breaths before these responses have a chance to undermine performance. The insula—where the body meets the brain—serves as the springboard from which athletic brilliance can soar.

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